The uterus-like mass (ULM) is a tumorlike anatomical entity originally described in the

ovary The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. ...

in 1981 and thereafter reported in several locations of the pelvis and abdominal cavity including

broad ligament The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis. Structure Subdivisions Contents The contents of the broad ligament include the following: * Reproduc ...

, greater omentum,

cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...

small intestine The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the ...

mesentery The mesentery is an organ that attaches the intestines to the posterior abdominal wall in humans and is formed by the double fold of peritoneum. It helps in storing fat and allowing blood vessels, lymphatics, and nerves to supply the intesti ...

and

conus medullaris ''Conus'' is a genus of predatory sea snails, or cone snails, marine gastropod mollusks in the family Conidae.Bouchet, P.; Gofas, S. (2015). Conus Linnaeus, 1758. In: MolluscaBase (2015). Accessed through: World Register of Marine Species at ...

. Basically, it is represented by a miniature uterus comprising a smooth muscle wall lined by endometrium thus outlining a uterus anatomical structure. Some of the reported cases have been associated to urinary tract and internal genitalia malformations whereas others appeared as a solitary finding. The term endomyometriosis has also been applied to this lesion. Different pathogenetic views have been suggested for this anomaly: a) a metaplastic change in

endometriosis Endometriosis is a disease of the female reproductive system in which cells similar to those in the endometrium, the layer of tissue that normally covers the inside of the uterus, grow outside the uterus. Most often this is on the ovaries, fall ...

foci bringing about smooth muscle

hyperplasia Hyperplasia (from ancient Greek ὑπέρ ''huper'' 'over' + πλάσις ''plasis'' 'formation'), or hypergenesis, is an enlargement of an organ or tissue caused by an increase in the amount of organic tissue that results from cell proliferatio ...

; b) a

congenital A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...

anomaly due to fusion defects of the

Müllerian ducts Paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fal ...

; and c) a sub-coelomic transformation of the

mesenchyme Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every ...

. ULM has also been reported associated to

endometrial carcinoma Endometrial cancer is a cancer that arises from the endometrium (the lining of the uterus or womb). It is the result of the abnormal growth of cells that have the ability to invade or spread to other parts of the body. The first sign is most of ...

and

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a r ...

. A clonal chromosome deletion 2p21 was found in endomyometriosis by Verhest et al. while Pai evidenced a strict relationship among ULM,

and elevated serum

CA125 Mucin-16 (MUC-16) also known as Ovarian cancer-related tumor marker CA125 is a protein that in humans is encoded by the ''MUC16'' gene. MUC-16 is a member of the mucin family glycoproteins. MUC-16 has found application as a tumor marker or biom ...

supporting the view of ULM being either hormone-dependent or a form of

. There have been reports of the finding of occurrence of endometriosis in leiomyomatosis peritonealis disseminata. More than 15 cases of ULM have been reported so far. A case of ULM was reported 22 years after total hysterectomy, another 17 years after. Abdominal pain and a palpable mass are among the main clinical findings. Anyway, the phenomenon of smooth muscle cell

metaplasia Metaplasia ( gr, "change in form") is the transformation of one differentiated cell type to another differentiated cell type. The change from one type of cell to another may be part of a normal maturation process, or caused by some sort of abno ...

occurring in association with endometriosis (endomyometriosis), as well as of smooth muscle differentiation at endometrio-myometrial junction independently from actually engendering uterus-like configurations in several locations of the pelvis, have been pointed out by several authors. A

magnetic resonance Magnetic resonance is a process by which a physical excitation (resonance) is set up via magnetism. This process was used to develop magnetic resonance imaging and Nuclear magnetic resonance spectroscopy technology. It is also being used to d ...

account of this lesion type has been provided by Menn et al.Menn KA, Qin L, Fedoriw G, Gillette ME, McCarthy S (2007). Uterus-like mass: MRI appearance of a very rare entity. JMRI 26(1):162-164.

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Further reading